Chi-yuan Hsu, MD, MSc is applying for a Mid-career Investigator Award in Patient Oriented Research (K24) in order to augment his original research and mentorship efforts. The new research to be supported by this grant leverages Dr. Hsu's ongoing funded projects and represents thematic expansions of his prior work. It is also designed to provide training opportunities for mentees. The underlying theme is to advance understanding of the significance and nature of acute deteriorations in kidney function on several fronts. The specific aims are: Aim 1: To determine the population incidence of acute renal failure (ARF)/acute kidney injury (AKI) overall and in clinically important subgroups and to determine potential driving forces behind this. Aim 2: To determine the importance of abrupt loss of renal function as a pathway leading directly from chronic kidney disease (CKD) to end-stage renal disease (ESRD). Aim 3: To determine the extent to which acute kidney function deterioration in the setting of acute heart failure is associated with elevated levels of markers of renal tubular injury. Dr. Hsu has a strong prior track record of mentorship and works within the rich, supportive and collegial institutional environment at UCSF. Funding from this K24 award will permit Dr. Hsu to spend less time on administrative and clinical responsibilities and more time on research and mentoring.